Sparking plug



Oct. 31, 1939. RUTHIARDT SPRKING PLUG Filed April 14, 193s Patented ocr. 31, 1939 UNlTEDsTATEs PATENT OFFICE- SPABKING PLUG Gustav Rutliardt, Stuttgart, Germany Y 3 Claims.

'I'his invention relates to a sparking plug for internal combustion engines for different kinds of fuel, in which the sparking plug housing is extended beyond the central electrode and forms a sparking chamber with a conically narrowing outflow passage and several sub-compartments of alternately increasing and decreasing cross-sectional area, the mass-electrode being arranged within the combustion chamber.

According to the invention the insulating body is mounted in a separate sleeve removablyin` serted yin the sparking plug body and secured thereon by a clamping nut. In the lower part of the sleeve the mass-electrodes are arranged which are connected with the central electrode xed in the insulating body. The insulating body with inserted central electrode in conjunction with the sleeve and the mass-electrodes forms a separate insertion which is placed in the sparking plug body after being adjusted. 'I'he insertion with sleeve in which the insulating body is iixed with the central electrode is removably inserted in the known sparking plug body and iixed by a screw cap. V'I'he central electrode .has a collar below the end of the insulating body, which collar aiords a particularlyeilective protection against the known objectionable cracking of the lower point of the insulating body. Thus, by means of.

the closed insertion, the mass-electrodes can .be accurately adjusted to the central electrode before being inserted in the sparking plug body. In sparking plugs with fore-chamber it was very difdcult if not impossible toeiect a precise mutual adjustment of the electrodes. By means of the separate insertion and the'iixation of the insulating body in the sleeve, the latter can be accurately set with care and attention, with the result that one-sided pressures on' the insulating body are prevented-this having not been possible in the known constructions in which it sometimes happens that? when inserting the insulating body in the sparking plug body, a one-'sided pressure is exerted on pressure and vthe great heat.

An embodiment of the invention is illustrated j companying drawing,

An insulating body b is inserted in-a sleeve a the insulating body which chipsv easily and leads to crackingunder Ythe explosion Application April 14, 1938, Serial No. 201,968

and xed by a clamping nut c.v For obtaining tight joints in the sleeve a packingrlng d is placed in the nut c and a packing ring e in the sleeve a. The ring f is xed in the lower part of the sleeve a in known manner, for example by bending over. 'I'he ring f is connected with the mass-electrodes g which can be very accurately set relatively to the central electrode h. The

central electrode h has at thelower end of the in-l sulating body b a collar i which protects the pointed end of the insulating body b against chipping. The central electrode h has no ,screw thread at its lower end, whereas its upper end has only a screw threaded extension for the nut for connecting up the cable. 'I'he whole insertion a, b, c, f and h is placed into'the sparking plug housing lc with the electrodes set and is fixed .therein by a screw cap l. Thus, it is possible to introduce the sparking plug insertion into the sparking chamber m with the electrodes accurately adjusted, with the result that any sub` sequent adjustment of the mass-electrodes g to the central electrode h is avoided. By unscrewing thecap l the insertion a, b, c can be removed directly from'the sparking plug housing k. 'Ihe sparking plug housing lchas an extension with combustion chamber of alternately increasing and decreasing cross-sectional area or with a central .bore owith helical groove p. Straight grooves may be provided in the central bore o instead of the helical groove p.

I claim: v

1. Sparking plug for internal combustion engines, comprising a sparking plug housing having abone end a compartment, an insulating body having a central bore, a central electrode in said bore and projecting slightly from the lower end of said body, a sleeve carrying said insulatingbody and projecting beyond the said projecting end of said vcentral electrode, mass-electrodes fixed in the lower end vof said sleeve and ldistributed around the periphery of said lprojecting end Aof said central 'electrode adjustably clamping said insulating body in said sleeve to determine the relative position of said central electrode and said mass-electrodes, a sparking plug housing having at its upper end a compartment adapted to accommodate said sleeve after the adjustment of said electrodes, a capv securing said sleeve in said compartment, and a screw-threaded extension at the lower end of said housing having a central bore communicating with said` compartment.

2. In a sparking plug as speciiled in claim 1, a collar on the projecting lower end of the central electrode at a distance from the extremity there'- of, said collar bearing against the lower end of the insulating body and forming a shield above the sparking gap between central electrode and mass-electrodes for protecting the insulating body against cracking. A

3. A sparking plug as specied in claim 1, in

which the compartment in the sparking plug housing has a tapered portion at its lower end below the iower edge of the sleeve, said tapered portion forming the sparking chamber, in which the bore in the extension tapers towards this 5 sparking chamber and has grooves in its wall.

GUSTAV RUTHARDT. 

